The contraction of molecular hydrogen protostars

Molecular hydrogen protostar contraction - stellar evolutio

Breakdown of helium nuclei in matter processed near black holes

The rate of breakup of helium nuclei by particle induced reactions is computed. It is shown that the rate is determined by the endothermic reaction p + 4He 3He + d, becoming effective at kT approx. few MeV. It is suggested that matter having been processed to these temperatures will be depleted in helium and in the elements C, N, O, and Ne

Phase space factors in multiparticle processes

General phase space theorems are discussed for the cases (A) with only energy conservation applied and (B) with energy and momentum conservation applied. It is shown that in the non-relativistic limit for N particles there is a very close relationship between the multiparticle phase space integral in case B and that for case A and N-1 particles

High energy photons and neutrinos from cosmic sources

High energy gamma and X-ray photons and neutrinos from cosmic sources - galactic radiatio

Observation of wave-packet propagation in the ion cyclotron range of frequencies in a tokamak plasma

Experimental observation of wave-packet propagation in the ion cyclotron range of frequencies in a tokamak plasma is reported. Studies were carried out in the Caltech Research Tokamak [Phys. Fluids 23, 614 (1980)] in a pure hydrogen plasma and in a regime where fast-wave damping was sufficiently small to permit multiple toroidal transits of the wave packet. Waves were launched by exciting a small loop antenna with a short burst of radio-frequency current and were detected with shielded magnetic probes. Probe scans revealed a large increase in wave-packet amplitude at smaller minor radii, and the packet velocity was found to be independent of radial position. Measurement of the packet transit time yielded direct information about the wave group velocity. Packet velocity was investigated as a function of the fundamental excitation frequency, plasma density, and toroidal magnetic field. Results are compared with the predictions of a cold plasma model that includes a vacuum layer at the edge

Fluorine negative ion detachment kinetics

A study of the rate of F(-) detachment by O and H atoms via the reactions F(-) + O yields FO + e and F(-) + H yields FH+ e was undertaken using a drift tube to produce F(-) ions at various drift velocities and therefore different ion temperatures. Preliminary mobility measurements of F(-) ions in Ar were made, indicating that ion temperatures in the 300 K to 5000 K range could be achieved; however due to numerous difficulties experienced in obtaining a reliable F(-) ion source, the study could not be completed

Lax Operator for the Quantised Orthosymplectic Superalgebra U_q[osp(2|n)]

Each quantum superalgebra is a quasi-triangular Hopf superalgebra, so contains a \textit{universal $R$-matrix} in the tensor product algebra which satisfies the Yang-Baxter equation. Applying the vector representation $\pi$, which acts on the vector module $V$, to one side of a universal $R$-matrix gives a Lax operator. In this paper a Lax operator is constructed for the $C$-type quantum superalgebras $U_q[osp(2|n)]$. This can in turn be used to find a solution to the Yang-Baxter equation acting on $V \otimes V \otimes W$ where $W$ is an arbitrary $U_q[osp(2|n)]$ module. The case $W=V$ is included here as an example.Comment: 15 page

Twisting invariance of link polynomials derived from ribbon quasi-Hopf algebras

The construction of link polynomials associated with finite dimensional representations of ribbon quasi-Hopf algebras is discussed in terms of the formulation of an appropriate Markov trace. We then show that this Markov trace is invariant under twisting of the quasi-Hopf structure, which in turn implies twisting invariance of the associated link polynomials.Comment: 18 pages, LaTeX, no figure

Local magnetic divertor for control of the plasma-limiter interaction in a tokamak

An experiment is described in which plasma flow to a tokamak limiter is controlled through the use of a local toroidal divertor coil mounted inside the limiter itself. This coil produces a local perturbed field B_C approximately equal to the local unperturbed toroidal field B_T ≃ 3 kG, such that when B_C adds to B_T the field lines move into the limiter and the local plasma flow to it increases by a factor as great as 1.6, and when B_C subtracts from B_T the field lines move away from the limiter and the local plasma flow to it decreases by as much as a factor of 4. A simple theoretical model is used to interpret these results. Since these changes occur without significantly affecting global plasma confinement, such a control scheme may be useful for optimizing the performance of pumped limiters

Galactic X-ray Sources

Bremsstrahlung and synchrotron hypotheses considered as possible mechanisms for galactic X-ray productio